Consulta: subjectFacets:"Carbon cycle"
Registros recuperados: 36
Data/hora: 09/06/2024 10:36:53

Monitoring and interpreting the ocean uptake of atmospheric CO2
Provedor de dados: 5
Autores: Watson, Andrew J.; Metzl, Nicolas; Schuster, Ute.
The oceans are an important sink for anthropogenically produced CO2, and on time scales longer than a century they will be the main repository for the CO2 that humans are emitting. Our knowledge of how ocean uptake varies (regionally and temporally) and the processes that control it is currently observation-limited. Traditionally, and based on sparse observations and models at coarse resolution, ocean uptake has been thought to be relatively invariant. However, in the few places where we have enough observations to define the uptake over periods of many years or decades, it has been found to change substantially at basin scales, responding to indices of climate variability. We illustrate this for three well-studied regions: the equatorial Pacific, the...
Tipo: Text
Palavras-chave: CO2; Carbon cycle; Greenhouse gases; Atmospheric oxygen.
Ano: 2011
URL: https://archimer.ifremer.fr/doc/00144/25561/23702.pdf

External Forcing Explains Recent Decadal Variability of the Ocean Carbon Sink
Provedor de dados: 5
Autores: Mckinley, Galen A.; Fay, Amanda R.; Eddebbar, Yassir A.; Gloege, Lucas; Lovenduski, Nicole S.
The ocean has absorbed the equivalent of 39% of industrial‐age fossil carbon emissions, significantly modulating the growth rate of atmospheric CO2 and its associated impacts on climate. Despite the importance of the ocean carbon sink to climate, our understanding of the causes of its interannual‐to‐decadal variability remains limited. This hinders our ability to attribute its past behavior and project its future. A key period of interest is the 1990s, when the ocean carbon sink did not grow as expected. Previous explanations of this behavior have focused on variability internal to the ocean or associated with coupled atmosphere/ocean modes. Here, we use an idealized upper ocean box model to illustrate that two external forcings are sufficient to explain...
Tipo: Text
Palavras-chave: Carbon cycle; Ocean carbon sink; Forced; Internal.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00676/78775/80950.pdf

Estimates of carbon flow through bacteriplankton in the S. Benguela upwelling region based on 3H-thymidine incorporation and predator-free incubations.
Provedor de dados: 5
Autores: Lucas, M; Painting, S; Muir, D.
Spatial and temporal estimates of bacterial numbers, biomass, activity and production were measured in the S. Benguela upwelling system during the course of a phytoplankton bloom. Bacterial numbers and biomass were highest in the euphotic zone and correlated closely with particulate carbon in the water column rather than with chlorophyll a concentrations. 3H-Thymidine incorporation gave good estimates of production. Differential utilisation of photosynthetic exudates and detrital POC by bacterioplankton during the course of a bloom might account for the varying significance ascribed to exudates and POC as a source of carbon for bacterial production.
Tipo: Text
Palavras-chave: Ecological associations; Algal blooms; Biomass; Microorganisms; Carbon cycle; Bacteria; Nannoplankton; Upwelling; Biogeochemistry.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-985.pdf

Long-term integrated biogeochemical budget driven by circulation in the eastern subpolar North Atlantic
Provedor de dados: 5
Autores: Fontela, Marcos; Mercier, Herle; Pérez, Fiz F.
The eastern subpolar North Atlantic (eSPNA) is a key region in the Atlantic Meridional Overturning Circulation (AMOC), playing an important role in biogeochemical cycles and climate regulation. Quantitative basin-scale biogeochemical budgets are still scarce despite the current need of establishing baselines of knowledge in a changing ocean. The physico-chemical data from the eight repetitions of the OVIDE section (2002-2016) are an unique opportunity to develop a novel evaluation of biogeochemical budgets in the eSPNA by combining robust and well established decadal mean mass transports with carbon variables, oxygen and inorganic nutrients in a full-depth inverse box model. The net balance between the carbon fixation and the respiration throughout the...
Tipo: Text
Palavras-chave: Subpolar North Atlantic; Biogeochemical cycles; Carbon cycle; Nutrient cycles; Oxygenation; Carbon sinks; Oceanic transports.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00480/59206/61898.pdf

Combining charcoal and elemental black carbon analysis in sedimentary archives: Implications for past fire regimes, the pyrogenic carbon cycle, and the human-climate interactions
Provedor de dados: 5
Autores: Thevenon, Florian; Williamson, David; Bard, Edouard; Anselmetti, Flavio S.; Beaufort, Luc; Cachier, Helene.
This paper addresses the quantification of combustion-derived products in oceanic and continental sediments by optical and chemical approaches, and the interest of combining such methods for reconstructing past biomass burning activity and the pyrogenic carbon cycle. In such context, the dark particles &gt;0.2 mu m(2) remaining after the partial digestion of organic matter are optically counted by automated image analysis and defined as charcoal, while the elemental carbon remaining after thermal and chemical oxidative treatments is quantified as black carbon (BC). The obtained pyrogenic carbon records from three sediment core-based case studies, (i) the Late Pleistocene equatorial Pacific Ocean. (ii) the mid-Holocene European Lake Lucerne, and (iii) the...
Tipo: Text
Palavras-chave: Biomass burning; Carbon cycle; Charcoal; Black carbon; Climate; Human impact.
Ano: 2010
URL: https://archimer.ifremer.fr/doc/00231/34198/32764.pdf

Evaluation of the heterotrophic activity in waters by microanalytical methods.
Provedor de dados: 5
Autores: Bertoni, R.
The radiochemical methods proposed for evaluating heterotrophic activity in waters have been severely criticized in recent years because they are not considered to be sufficiently realistic. Thus, the possibility of directly measuring the heterotrophic consumption of naturally occurring Organic Carbon (OC) in fresh water samples incubated under controlled conditions has been evaluated. The analytical performances of two OC analyzers utilizable for this purpose are discussed here, and some examples of the results obtained by the direct measurement of OC consumption are presented. The consumption rates thus measured ranged from 11.6 to 50.2 mu gC/ 1.h. Although the technique discussed here is less sensitive than radiochemical methods, the few assumptions...
Tipo: Text
Palavras-chave: Biogeochemistry; Microbiology; Carbon cycle; Organic carbon; Water; Heterotrophic organisms; Analytical techniques.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-950.pdf

Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5
Provedor de dados: 5
Autores: Dufresne, J-l.; Foujols, M-a.; Denvil, S.; Caubel, A.; Marti, O.; Aumont, Olivier; Balkanski, Y.; Bekki, S.; Bellenger, H.; Benshila, R.; Bony, S.; Bopp, L.; Braconnot, P.; Brockmann, P.; Cadule, P.; Cheruy, F.; Codron, F.; Cozic, A; Cugnet, D.; De Noblet, N.; Duvel, J-p.; Ethe,; Fairhead, L.; Fichefet, T.; Flavoni, S.; Friedlingstein, P.; Grandpeix, J-y.; Guez, L.; Guilyardi, E.; Hauglustaine, D.; Hourdin, F.; Idelkadi, A.; Ghattas, J.; Joussaume, S.; Kageyama, M.; Krinner, G.; Labetoulle, S.; Lahellec, A.; Lefebvre, M; Lefevre, F.; Levy, C.; Li, Zhanbin; Lloyd, J.; Lott, F.; Madec, G.; Mancip, M.; Marchand, M; Masson, S.; Meurdesoif, Y.; Mignot, J.; Musat, I.; Parouty, S.; Polcher, J.; Rio, C; Schulz, M.; Swingedouw, D.; Szopa, S.; Talandier, Claude; Terray, P.; Viovy, N.; Vuichard, N.
We present the global general circulation model IPSL-CM5 developed to study the long-term response of the climate system to natural and anthropogenic forcings as part of the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). This model includes an interactive carbon cycle, a representation of tropospheric and stratospheric chemistry, and a comprehensive representation of aerosols. As it represents the principal dynamical, physical, and bio-geochemical processes relevant to the climate system, it may be referred to as an Earth System Model. However, the IPSL-CM5 model may be used in a multitude of configurations associated with different boundary conditions and with a range of complexities in terms of processes and interactions. This paper...
Tipo: Text
Palavras-chave: Climate; Climate change; Climate projections; Earth System Model; CMIP5; CMIP3; Greenhouse gases; Aerosols; Carbon cycle; Allowable emissions; RCP scenarios; Land use changes.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00138/24966/23079.pdf

Millennial scale persistence of organic carbon bound to iron in Arctic marine sediments
Provedor de dados: 5
Autores: Faust, Johan C.; Tessin, Allyson; Fisher, Ben J.; Zindorf, Mark Sebastian; Papadaki, Sonia; Hendry, Katharine R.; Doyle, Katherine A.; März, Christian.
Burial of organic material in marine sediments represents a dominant natural mechanism of long-term carbon sequestration globally, but critical aspects of this carbon sink remain unresolved. Investigation of surface sediments led to the proposition that on average 10-20% of sedimentary organic carbon is stabilised and physically protected against microbial degradation through binding to reactive metal (e.g. iron and manganese) oxides. Here we examine the long-term efficiency of this rusty carbon sink by analysing the chemical composition of sediments and pore waters from four locations in the Barents Sea. Our findings show that the carbon-iron coupling persists below the uppermost, oxygenated sediment layer over thousands of years. We further propose that...
Tipo: Text
Palavras-chave: Carbon cycle; Geochemistry.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00675/78755/80923.pdf

Nonuniform ocean acidification and attenuation of the ocean carbon sink
Provedor de dados: 5
Autores: Fassbender, Andrea J.; Sabine, Christopher L.; Palevsky, Hilary I.
Surface ocean carbon chemistry is changing rapidly. Partial pressures of carbon dioxide gas (pCO(2)) are rising, pH levels are declining, and the ocean's buffer capacity is eroding. Regional differences in short-term pH trends primarily have been attributed to physical and biological processes; however, heterogeneous seawater carbonate chemistry may also be playing an important role. Here we use Surface Ocean CO2 Atlas Version 4 data to develop 12month gridded climatologies of carbonate system variables and explore the coherent spatial patterns of ocean acidification and attenuation in the ocean carbon sink caused by rising atmospheric pCO(2). High-latitude regions exhibit the highest pH and buffer capacity sensitivities to pCO(2) increases, while the...
Tipo: Text
Palavras-chave: Ocean acidification; Carbon sink; Revelle factor; Carbon cycle.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00661/77321/78794.pdf

Ocean Circulation Drives the Variability of the Carbon System in the Eastern Tropical Atlantic
Provedor de dados: 5
Autores: Lefèvre, Nathalie; Mejia, Carlos; Khvorostyanov, Dmitry; Beaumont, Laurence; Koffi, Urbain.
The carbon system in the eastern tropical Atlantic remains poorly known. The variability and drivers of the carbon system are assessed using surface dissolved inorganic carbon (DIC), alkalinity (TA) and fugacity of CO2 (fCO2) measured in the 12° N–12° S, 12° W–12° E region from 2005 to 2019. A relationship linking DIC to temperature, salinity and year has been determined, with salinity being the strongest predictor. The seasonal variations of DIC, ranging from 80 to 120 mol kg−1, are more important than the year-to-year variability that is less than 50 mol kg−1 over the 2010–2019 period. DIC and TA concentrations are lower in the northern part of the basin where surface waters are fresher and warmer. Carbon supply dominates over biological carbon uptake...
Tipo: Text
Palavras-chave: Carbon cycle; Tropical Atlantic; Dissolved inorganic carbon; Alkalinity.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00678/79046/81494.pdf

Nutrients and carbon budgets for the Gulf of Lion during the Moogli cruises
Provedor de dados: 5
Autores: Durrieu De Madron, X; Denis, L; Diaz, F; Garcia, N; Guieu, C; Grenz, C; Loye-pilot, Md; Ludwig, W; Moutin, T; Raimbault, P; Ridame, C.
Shelf-slope exchanges and budgets of organic and inorganic nutrients are calculated for the Gulf of Lion continental margin in the northwestern Mediterranean. Computations are based on data from three seasonal marine surveys performed in March 1998, June 1998 and January 1999 in the framework of the French Programme National d'Environnement Cotier. A Land-Ocean Interactions in the Coastal Zone type box model is used to calculate the advective exchanges between the shelf and the adjacent open sea and to estimate the budgets of non-conservative elements (DIP, DIN, DOP, DON, DOC, POC, PON, POP). These budgets consider river discharges, urban sewage supply, atmospheric deposition, and fluxes at the water-sediment and shelf-slope interfaces. Uncertainties on...
Tipo: Text
Palavras-chave: Mer Méditerranée; Echanges côte-large; Fonctionnement de l’écosystème; Cycle du carbone; Bilan de sels nutritifs; Mediterranean Sea; Shelf-slope exchanges; Ecosystem functioning; Carbon cycle; Nutrients budget.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00301/41236/40426.pdf

Seasonal and vertical variations of sinking particle fluxes in the West Caroline Basin
Provedor de dados: 5
Autores: Kawahata, H; Yamamuro, M; Ohta, H.
A sediment trap experiment was carried out in the West Caroline Basin, located in the equatorial western Pacific between influences of the Asian monsoon and the open ocean. Annual mass flux at the shallow trap at Site 1 was 57.10 g m(-2)yr(-1). Generally, the higher flux of organic matter was associated with higher activities of biogenic opal-producing and carbonate-producing plankton communities. In addition, as the organic matter content increases, the organic carbon/carbonate carbon ratio shows a tendency to increase. Carbonate-producing plankton was predominant during periods 1 and 3 (May to July and November to the beginning of December), which could be due to limited silica supply to the euphotic zone. On the other hand, surface sea water was more...
Tipo: Text
Palavras-chave: Variation saisonnière; Variation verticale; Flux de particules; Pacifique occidental; Cycle du carbone; Seasonality; Vertical variations; Sinking particle fluxes; Western Pacific; Carbon cycle.
Ano: 1998
URL: http://archimer.ifremer.fr/doc/00325/43655/43219.pdf

A laboratory model system for analysing microbial interactions occurring in anoxic estuarine sediments.
Provedor de dados: 5
Autores: Herbert, R; Keith, S.
Defined mixed populations of Clostridium butyricum, Desulfovibrio desulfuricans and Chromatium vinosum co-existed for long periods when grown in a single stage chemostat with glucose as sole carbon source. The nature and availability of the inorganic nitrogen source exerted a major effect on carbon flow in the experimental system. The data show that both the C. butyricum and D. desulfuricans isolates can utilise NO sub(3) as an e super(-)acceptor with an increase in cell yield. Under these growth conditions the free S super(2-) levels were lower resulting in more stable mixed populations. In addition the data show that the C. butyricum produces more oxidised fermentation end-products (acetate) when NO sub(3) super(-) was available and more reduced products...
Tipo: Text
Palavras-chave: Chromatium vinosum; Desulfovibrio desulfuricans; Clostridium butyricum; Biogeochemistry; Models; Bacteria; Detritus; Mineralization; Anoxic sediments; Estuarine sedimentation; Analytical techniques; Carbon cycle; Interspecific relationships; Microbiology.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-947.pdf

Organic matter in sediments in the mangrove areas and adjacent continental margins of Brazil .1. Amino acids and hexosamines
Provedor de dados: 5
Autores: Jennerjahn, Tc; Ittekkot, V.
The nature of sedimentary organic matter from mangroves and the continental margin of eastern Brazil (8 degrees-24 degrees S) has been investigated in order to obtain information on sources and diagenetic processes. The organic matter content of mangrove sediments is three to four times higher than the maximum content of continental margin sediments. Downslope distribution of organic carbon, nitrogen, amino acids and hexosamines shows an enrichment in water depths between 800 m and 1000 m. The distribution of individual amino acids and hexosamines is highly variable in sedimentary organic matter from mangroves and the continental margin, and the observed compositional differences are mainly due to diagenetic alteration. Organic matter is highly reactive in...
Tipo: Text
Palavras-chave: Organic carbon; Amino acids; Carbon cycle; Mangroves; Continental margin.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00093/20403/18070.pdf

Radiocarbon Evidence for the Contribution of the Southern Indian Ocean to the Evolution of Atmospheric CO     2     over the last 32,000 years
Provedor de dados: 5
Autores: Ronge, Thomas A.; Prange, M.; Mollenhauer, Gesine; Ellinghausen, Maret; Kuhn, G.; Tiedemann, R.
It is widely assumed that the ventilation of the Southern Ocean played a crucial role in driving glacial‐interglacial atmospheric CO2‐levels. So far however, ventilation records from the Indian sector of the Southern Ocean, are widely missing. Here we present reconstructions of water residence times (depicted as ΔΔ14C and Δδ13C) for the last 32,000 years on sediment records from the Kerguelen Plateau and the Conrad Rise (~570‐2500 m water depth), along with simulated changes in ocean stratification from a transient climate model experiment. Our data indicate that Circumpolar Deep Waters in the Indian Ocean were part of the glacial carbon pool. At our sites, close to or bathed by upwelling deep‐waters, we find two pulses of decreasing ΔΔ14C and δ13C values...
Tipo: Text
Palavras-chave: Radiocarbon; Ventilation; Southern Ocean; Younger Dryas; Carbon cycle; Indian Ocean.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00611/72351/71258.pdf

Assessments of anthropogenic CO2 distribution in the tropical Atlantic Ocean
Provedor de dados: 5
Autores: Touratier, Franck; Goyet, C; Coatanoan, Christine; Andrie, C.
With a limited number of properties (salinity, temperature, total dissolved inorganic carbon, total alkalinity, and oxygen) from a recent cruise in the tropical Atlantic Ocean, We use the simple and recent approach TrOCA (Tracer combining Oxygen, inorganic Carbon, and total Alkalinity) to estimate the distribution of anthropogenic CO2 along three latitudinal sections. In order to assess the quality of the anthropogenic CO2 distribution, results from the method are compared to the CFC-11 measurements. We discuss the large-scale distribution of the main water masses of the tropical Atlantic Ocean in the light of the anthropogenic CO2 and the CFC-11 distributions. Keeping in mind that the anthropogenic CO2 emission began similar to 60 years earlier than that...
Tipo: Text
Palavras-chave: Tropical belt; Atlantic Ocean; Water mass; Carbon cycle.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/2005/publication-886.pdf

On which timescales do gas transfer velocities control North Atlantic CO2 flux variability?
Provedor de dados: 5
Autores: Couldrey, Matthew P.; Oliver, Kevin I. C.; Yool, Andrew; Halloran, Paul R.; Achterberg, Eric P.
The North Atlantic is an important basin for the global ocean's uptake of anthropogenic and natural carbon dioxide (CO2), but the mechanisms controlling this carbon flux are not fully understood. The air-sea flux of CO2, F, is the product of a gas transfer velocity, k, the air-sea CO2 concentration gradient, Delta pCO(2), and the temperature-and salinity-dependent solubility coefficient, alpha, k is difficult to constrain, representing the dominant uncertainty in F on short (instantaneous to interannual) timescales. Previous work shows that in the North Atlantic, Delta pCO(2) and k both contribute significantly to interannual F variability but that k is unimportant for multidecadal variability. On some timescale between interannual and multidecadal, gas...
Tipo: Text
Palavras-chave: Carbon flux; Gas transfer velocity; Carbon cycle; Ocean model; Climate dynamics; Variability.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00383/49418/49868.pdf

Metabolism of CO and CH sub(4) by nitrifiers and the determination of the nitrification rate.
Provedor de dados: 5
Autores: Morita, R; Jones, R.
The nitrifying bacteria were found to survive 24 weeks in the absence of ammonium without decreasing their number of cell size. Because H sub(2), CO, and CH sub(4) are present in the marine environment, these substrates were investigated as a possible source of the energy of maintenance for the nitrifying bacteria. super(14)CO and super(14)CH sub(4) were found to be oxidized by the nitrifiers. N-serve was found to inhibit the oxidation of CO. Using the nitrifiers' ability to oxide CO, a method for the determination of the nitrification rate was developed. The ability of nitrifiers to oxidize CO may play a significant role in the cycling of CO sub(2) in the marine environment. Whether CO and CH sub(4) oxidation play a role in the survival of nitrifiers in...
Tipo: Text
Palavras-chave: Methane; Carbon dioxide; Survival; Bacteria; Nitrification; Nitrogen cycle; Oxidation; Carbon cycle; Biogeochemistry; Metabolism.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-975.pdf

Variability of the Ocean Carbon Cycle in Response to the North Atlantic Oscillation
Provedor de dados: 5
Autores: Keller, Kathrin M.; Joos, Fortunat; Raible, Christoph C.; Cocco, Valentina; Froelicher, Thomas L.; Dunne, John P.; Gehlen, Marion; Bopp, Laurent; Orr, James C.; Tjiputra, Jerry; Heinze, Christoph; Segschneider, Joachim; Roy, Tilla; Metzl, Nicolas.
Climate modes such as the North Atlantic Oscillation (NAO), representing internal variability of the climate system, influence the ocean carbon cycle and may mask trends in the sink of anthropogenic carbon. Here, utilising control runs of six fully coupled Earth System Models, the response of the ocean carbon cycle to the NAO is quantified. The dominating response, a seesaw pattern between the subtropical gyre and the subpolar Northern Atlantic, is instantaneous (&lt;3 months) and dynamically consistent over all models and with observations for a range of physical and biogeochemical variables. All models show asymmetric responses to NAO+ and NAO− forcing, implying non-linearity in the connection between NAO and the ocean carbon cycle. However, model...
Tipo: Text
Palavras-chave: North Atlantic Oscillation; Carbon cycle; Ocean biogeochemistry; Climate modeling; Ocean-atmosphere interaction.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00140/25166/23272.pdf

Variability in benthic oxygen fluxes during the winter-spring transition in coastal sediments: an estimation by in situ micro-electrodes and laboratory mini-electrodes
Provedor de dados: 5
Autores: Lansard, B; Rabouille, C; Massias, D.
Two expeditions were achieved at the winter-spring transition in the Golfe de Fos (Mediterranean Sea) at a site situated at 21 m depth. An in situ autonomous oxygen profiler and laboratory oxygen mini-electrodes were used to measure the oxygen distribution in the sediments and calculate the diffusive oxygen fluxes. Clearer waters during the second expedition promoted a rapid shift from a net heterotrophic environment to a photosynthesis-dominated sediment. The diffusive exchange fluxes of oxygen through the sediment-water interface varied from an average consumption of 5.3 mmol m(-2) d(-1) (February) to a net production of 12 mmol m(-2) d(-1) (March). At both periods, a large spatial heterogeneity was recorded by the different electrodes, with a larger...
Tipo: Text
Palavras-chave: Oxygène; Micro-électrodes in situ; Biogéochimie; Cycle du carbone; Sédiment côtier; Oxygen; In situ micro-electrodes; Biogeochemistry; Carbon cycle; Coastal sediment.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00322/43272/43003.pdf

Decadal evolution of carbon sink within a strong bloom area in the subantarctic zone
Provedor de dados: 5
Autores: Lourantou, Anna; Metzl, Nicolas.
The fate of the Southern Ocean atmospheric CO(2) sink is under question. Here we assess seasonal to decadal changes of surface fCO(2) within an extended sink area along the track between Kerguelen and Amsterdam islands in the subantarctic zone. Data from 17 oceanographic cruises were used, from 1991 to 2011 and two distinct regions were examined, separated by the Subantarctic Front (SAF). The region south of the SAF displays a strong summer phytoplankton bloom of up to -28 mmol C m(-2) d(-1) within a calm area, constrained by physics and topography. On an annual basis, this region is a 6-fold more important sink than that deduced from Takahashi climatology, highlighting the importance of key-areas separate examination before proceeding to spatial...
Tipo: Text
Palavras-chave: Kerguelen; Air-sea CO2 fluxes; Carbon cycle; Frontal region; Island mass effect; Subantarctic zone.
Ano: 2011
URL: https://archimer.ifremer.fr/doc/00144/25557/23706.pdf

Regionalized global budget of the CO2 exchange at the air-water interface in continental shelf seas
Provedor de dados: 5
Autores: Laruelle, Goulven G.; Lauerwald, Ronny; Pfeil, Benjamin; Regnier, Pierre.
Over the past decade, estimates of the atmospheric CO2 uptake by continental shelf seas were constrained within the 0.18-0.45 Pg C yr(-1) range. However, most of those estimates are based on extrapolations from limited data sets of local flux measurements (n&lt;100). Here we propose to derive the CO2 air-sea exchange of the shelf seas by extracting 310(6) direct surface ocean CO2 measurements from the global database SOCAT (Surface Ocean CO2 Atlas), atmospheric CO2 values from GlobalVIEW and calculating gas transfer rates using readily available global temperature, salinity, and wind speed fields. We then aggregate our results using a global segmentation of the shelf in 45 units and 152 subunits to establish a consistent regionalized CO2 exchange budget at...
Tipo: Text
Palavras-chave: CO2; Coastal ocean; Carbon cycle.
Ano: 2014
URL: https://archimer.ifremer.fr/doc/00293/40426/38969.pdf

Seasonal Asymmetry in the Evolution of Surface Ocean pCO(2) and pH Thermodynamic Drivers and the Influence on Sea-Air CO2 Flux
Provedor de dados: 5
Autores: Fassbender, Andrea J.; Rodgers, Keith B.; Palevsky, Hilary I.; Sabine, Christopher L.
It has become clear that anthropogenic carbon invasion into the surface ocean drives changes in the seasonal cycles of carbon dioxide partial pressure (pCO(2)) and pH. However, it is not yet known whether the resulting sea-air CO2 fluxes are symmetric in their seasonal expression. Here we consider a novel application of observational constraints and modeling inferences to test the hypothesis that changes in the ocean's Revelle factor facilitate a seasonally asymmetric response in pCO(2) and the sea-air CO2 flux. We use an analytical framework that builds on observed sea surface pCO(2) variability for the modern era and incorporates transient dissolved inorganic carbon concentrations from an Earth system model. Our findings reveal asymmetric amplification...
Tipo: Text
Palavras-chave: Revelle Factor; Carbon cycle; Seasonal cycle; CO2 fluxes; Ocean acidification.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00675/78679/80884.pdf

Impact of Nonzero Intercept Gas Transfer Velocity Parameterizations on Global and Regional Ocean-Atmosphere CO2 Fluxes
Provedor de dados: 5
Autores: Ribas-ribas, Mariana; Battaglia, Gianna; Humphreys, Matthew P.; Wurl, Oliver.
Carbon dioxide (CO2) fluxes between the ocean and atmosphere (FCO2) are commonly computed from differences between their partial pressures of CO2 (pCO(2)) and the gas transfer velocity (k). Commonly used wind-based parameterizations for k imply a zero intercept, although in situ field data below 4 m s(-1) are scarce. Considering a global average wind speed over the ocean of 6.6 m s(-1), a nonzero intercept might have a significant impact on global FCO2. Here, we present a database of 245 in situ measurements of k obtained with the floating chamber technique (Sniffle), 190 of which have wind speeds lower than 4 m s(-1). A quadratic parameterization with wind speed and a nonzero intercept resulted in the best fit for k. We further tested FCO2 calculated with...
Tipo: Text
Palavras-chave: Gas transfer velocity; Low wind speed; Carbon dioxide; Ocean-atmosphere CO2 flux; Carbon cycle.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00675/78732/80994.pdf

Seasonally different carbon flux changes in the Southern Ocean in response to the southern annular mode
Provedor de dados: 5
Autores: Hauck, J.; Voelker, C.; Wang, T.; Hoppema, M.; Losch, M.; Wolf-gladrow, D. A.
Stratospheric ozone depletion and emission of greenhouse gases lead to a trend of the southern annular mode (SAM) toward its high-index polarity. The positive phase of the SAM is characterized by stronger than usual westerly winds that induce changes in the physical carbon transport. Changes in the natural carbon budget of the upper 100 m of the Southern Ocean in response to a positive SAM phase are explored with a coupled ecosystem-general circulation model and regression analysis. Previously overlooked processes that are important for the upper ocean carbon budget during a positive SAM period are identified, namely, export production and downward transport of carbon north of the polar front (PF) as large as the upwelling in the south. The limiting...
Tipo: Text
Palavras-chave: Southern Ocean; Southern annular mode; Carbon cycle; Carbon sink.
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00292/40352/38988.pdf

Radiocarbon evidence for alternating northern and southern sources of ventilation of the deep Atlantic carbon pool during the last deglaciation
Provedor de dados: 5
Autores: Skinner, Luke C.; Waelbroeck, Claire; Scrivner, Adam E.; Fallon, Stewart J.
Recent theories for glacial-interglacial climate transitions call on millennial climate perturbations that purged the deep sea of sequestered carbon dioxide via a "bipolar ventilation seesaw." However, the viability of this hypothesis has been contested, and robust evidence in its support is lacking. Here we present a record of North Atlantic deep-water radiocarbon ventilation, which we compare with similar data from the Southern Ocean. A striking coherence in ventilation changes is found, with extremely high ventilation ages prevailing across the deep Atlantic during the last glacial period. The data also reveal two reversals in the ventilation gradient between the deep North Atlantic and Southern Ocean during Heinrich Stadial 1 and the Younger Dryas....
Tipo: Text
Palavras-chave: Ocean circulation; Carbon cycle; Abrupt change.
Ano: 2014
URL: https://archimer.ifremer.fr/doc/00290/40153/39327.pdf

Freshwater and its role in the Arctic Marine System: sources, disposition, storage, export, and physical and biogeochemical consequences in the Arctic and global oceans
Provedor de dados: 5
Autores: Carmack, E. C.; Yamamoto-kawai, M.; Haine, T. W. N.; Bacon, S.; Bluhm, B. A.; Lique, Camille; Melling, H.; Polyakov, I. V.; Straneo, F.; Timmermans, M. -l.; Williams, W. J.
The Arctic Ocean is a fundamental node in the global hydrological cycle and the ocean's thermohaline circulation. We here assess the system's key functions and processes: 1) the delivery of fresh and low salinity waters to the Arctic Ocean by river inflow, net precipitation, distillation during the freeze/thaw cycle and Pacific Ocean inflows; 2) the disposition (e.g. sources, pathways and storage) of freshwater components within the Arctic Ocean; and 3) the release and export of freshwater components into the bordering convective domains of the North Atlantic. We then examine physical, chemical or biological processes which are influenced or constrained by the local quantities and geochemical qualities of fresh water; these include: stratification and...
Tipo: Text
Palavras-chave: Arctic; Oceans; Circulation; Freshwater; Carbon cycle; Acidification.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00313/42460/41831.pdf

Atlantic Ocean ventilation changes across the last deglaciation and their carbon cycle implications
Provedor de dados: 5
Autores: Skinner, L. C.; Freeman, E.; Hodell, D.; Waelbroeck, C.; Vazquez Riveiros, Natalia; Scrivner, A.e.
Changes in ocean ventilation, controlled by both overturning rates and air‐sea gas exchange, are thought to have played a central role in atmospheric CO2 rise across the last deglaciation. Here we constrain the nature of Atlantic Ocean ventilation changes over the last deglaciation using radiocarbon and stable carbon isotopes from two depth transects in the Atlantic basin. Our findings broadly cohere with the established pattern of deglacial Atlantic overturning change, and underline the existence of active northern sourced deep‐water export at the Last Glacial Maximum (LGM). We find that the western Atlantic was less affected by incursions of southern‐sourced deep water, as compared to the eastern Atlantic, despite both sides of the basin being strongly...
Tipo: Text
Palavras-chave: Air&amp;#8208; Sea exchange; AMOC; Carbon cycle; Deglaciation; Radiocarbon; Ventilation.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00665/77717/79810.pdf

An Alternative to Static Climatologies: Robust Estimation of Open Ocean CO2 Variables and Nutrient Concentrations From T, S, and O-2 Data Using Bayesian Neural Networks
Provedor de dados: 5
Autores: Bittig, Henry C.; Steinhoff, Tobias; Claustre, Harve; Fiedler, Bjoern; Williams, Nancy L.; Sauzede, Raphaelle; Koertzinger, Arne; Gattuso, Jean-pierre.
This work presents two new methods to estimate oceanic alkalinity (A(T)), dissolved inorganic carbon (C-T), pH, and pCO(2) from temperature, salinity, oxygen, and geolocation data. "CANYON-B" is a Bayesian neural network mapping that accurately reproduces GLODAPv2 bottle data and the biogeochemical relations contained therein. "CONTENT" combines and refines the four carbonate system variables to be consistent with carbonate chemistry. Both methods come with a robust uncertainty estimate that incorporates information from the local conditions. They are validated against independent GO-SHIP bottle and sensor data, and compare favorably to other state-of-the-art mapping methods. As "dynamic climatologies" they show comparable performance to classical...
Tipo: Text
Palavras-chave: Carbon cycle; GLODAP; Marine carbonate system; Surface pCO(2) climatology; Revelle buffer factor increase; Machine learning; Nutrient estimation.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00675/78681/80879.pdf

When can ocean acidification impacts be detected from decadal alkalinity measurements?
Provedor de dados: 5
Autores: Carter, B. R.; Frolicher, T. L.; Dunne, J. P.; Rodgers, K. B.; Slater, R. D.; Sarmiento, J. L.
We use a large initial condition suite of simulations (30 runs) with an Earth system model to assess the detectability of biogeochemical impacts of ocean acidification (OA) on the marine alkalinity distribution from decadally repeated hydrographic measurements such as those produced by the Global Ship-Based Hydrographic Investigations Program (GO-SHIP). Detection of these impacts is complicated by alkalinity changes from variability and long-term trends in freshwater and organic matter cycling and ocean circulation. In our ensemble simulation, variability in freshwater cycling generates large changes in alkalinity that obscure the changes of interest and prevent the attribution of observed alkalinity redistribution to OA. These complications from...
Tipo: Text
Palavras-chave: Alkalinity; Ocean acidification; Trend detection; Repeat hydrography; Carbon cycle; Carbonate system.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00383/49419/49860.pdf

A BGC-Argo Guide: Planning, Deployment, Data Handling and Usage
Provedor de dados: 5
Autores: Bittig, Henry C.; Maurer, Tanya L.; Plant, Joshua N.; Schmechtig, Catherine; Wong, Annie P. S.; Claustre, Hervé; Trull, Thomas W.; Udaya Bhaskar, T. V. S.; Boss, Emmanuel; Dall’olmo, Giorgio; Organelli, Emanuele; Poteau, Antoine; Johnson, Kenneth S.; Hanstein, Craig; Leymarie, Edouard; Le Reste, Serge; Riser, Stephen C.; Rupan, A. Rick; Taillandier, Vincent; Thierry, Virginie; Xing, Xiaogang.
The Biogeochemical-Argo program (BGC-Argo) is a new profiling-float-based, ocean wide, and distributed ocean monitoring program which is tightly linked to, and has benefited significantly from, the Argo program. The community has recommended for BGC-Argo to measure six additional properties in addition to pressure, temperature and salinity measured by Argo, to include oxygen, pH, nitrate, downwelling light, chlorophyll fluorescence and the optical backscattering coefficient. The purpose of this addition is to enable the monitoring of ocean biogeochemistry and health, and in particular, monitor major processes such as ocean deoxygenation, acidification and warming and their effect on phytoplankton, the main source of energy of marine ecosystems. Here we...
Tipo: Text
Palavras-chave: Ocean observation; Ocean biogeochemical cycles; Sensors; Carbon cycle; Ocean optics; Best practices; Argo.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00512/62344/66607.pdf

Polychaete tube walls as zonated microhabitats for marine bacteria.
Provedor de dados: 5
Autores: Reichardt, W.
The predominantly anoxic, sulfide-rich sandy sediment of a shallow lagoon at Kiel Fjord was densely inhabited by the polychaete worm Nereis diversicolor (280 cm super(3) m super(-2) of biomass volume). Burrow walls which contrasted by their brown coloration of at least 1.5 mm thickness with the bulk of the reduced black sediment, made up for 6% of the total volume of the 10 cm cores investigated. Only the uppermost mm of the internal surface layer contained detectable O sub(2). As a result of the build up of internal redox gradients, CO sub(2) dark fixation was activated in the burrow walls (by a factor of approximately equals 2). Assays of ribulose-biphosphate carboxylase activities and viable counts of potentially chemoautotrophic bacteria in different...
Tipo: Text
Palavras-chave: Nereis diversicolor; Polychaeta; Bacteria; Microorganisms; Carbon cycle; Tube dwellers; Carbon fixation; Burrows; Bioturbation; Sediments.
Ano: 1984
URL: http://archimer.ifremer.fr/doc/1984/acte-990.pdf

マニュアスプレッダの堆肥散布機構と散布精度
Provedor de dados: 19
Autores: 申, 宝明; 佐藤, 禎稔; 岸本, 正; 谷, 昌幸; 仙北谷, 康; 加藤, 拓; 林, 芙俊; SHEN, Baoming; SATOW, Tadatoshi; KISHIMOTO, Tadashi; TANI, Masayuki; SENBOKUYA, Yasushi; KATO, Taku; HAYASHI, Futoshi.
マニュアスプレッダによる堆肥の散布精度の現状を把握することを目的とし，横軸ピータ型，縦軸ビータ型，左側方散布型の3機種を対象として堆肥の散布量分布および 堆肥散布精度の調査を行った。各機種の散布量分布は，いずれも山型の形状を示しており，横軸ビータ型，縦軸ピータ型では，マニュアスプレッダの中心から左右1m以内に，それぞれ全体の76%，40%が散布され，左側方散布型は左側3-5mの範囲に全体の71%が集中して散布された。最大散布畳は横軸ビータ型が2.3t/l0a，縦軸ビータ型が6.5t/10a，左側方散布型が10.3t/l0aとなり，重複散布しても規定散布量である2t/l0aが望めない結果となった。また，圃場全体の堆肥散布量は各機種で0.2-3.4t/lOa，2.4-22. 8t/l0a，0.6-5.0t/10aであり， 堆肥の性状によって散布むらが大きくなることが判明した。The purpose of this study was to investigate the present situation of compost spreading with manure spreaders in Tokachi region. Therefore，three different types of manure spreaders: rear horizontal beater type(A)，vertical beater type (B) and side discharge type (C)，were used to determine the application pattern and accuracy of compost spreading. Application pattern of each...
Palavras-chave: 堆肥の利用; マッピング; 炭素循環; 精密農法; Utilization of compost; Mapping; Carbon cycle; Precision farming.
Ano: 2010
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/2701

Compuestos del ciclo del carbono en la zona litoral del municipio Playa, Ciudad de la Habana, Cuba.
Provedor de dados: 20
Autores: Montalvo, J. F.; García, I.; Esponda, S.C.,; Cesar, M.E.; Alburquerque, O.
Se realizaron cinco muestreos entre enero de 2007 y junio de 2008 a la zona costera del municipio Playa, con el fin de evaluar los contenidos de los compuestos del ciclo del carbono. Los parámetros estudiados en la matriz agua fueron carbón orgánico, pH, alcalinidad total, alcalinidad al carbonato, dióxido de carbono total, dióxido de carbono libre, presión parcial de CO2, y contenidos de bicarbonato y carbonato. Los compuestos de carbono orgánico e inorgánico tuvieron una distribución muy heterogénea, los valores de pH (8,24±0,22) y alcalinidad total (2523±119 μmol/kg) indican que el área tiene un comportamiento alcalino, estos montos fueron similares a los encontrados en aguas de la plataforma marina cubanos y superiores a los consignados para el...
Tipo: Journal Contribution
Palavras-chave: Carbon dioxide; Alkalinity; Carbon cycle; Carbon dioxide; Alkalinity; Carbon cycle; Http://aims.fao.org/aos/agrovoc/c_1302; Http://aims.fao.org/aos/agrovoc/c_8721; Http://aims.fao.org/aos/agrovoc/c_17299.
Ano: 2009
URL: http://hdl.handle.net/1834/3390

Estimating of gross primary production in an Amazon-Cerrado transitional forest using MODIS and Landsat imagery
Provedor de dados: 42
Autores: DANELICHEN,VICTOR H.M.; BIUDES,MARCELO S.; VELASQUE,MAÍSA C.S.; MACHADO,NADJA G.; GOMES,RAPHAEL S.R.; VOURLITIS,GEORGE L.; NOGUEIRA,JOSÉ S.
The acceleration of the anthropogenic activity has increased the atmospheric carbon concentration, which causes changes in regional climate. The Gross Primary Production (GPP) is an important variable in the global carbon cycle studies, since it defines the atmospheric carbon extraction rate from terrestrial ecosystems. The objective of this study was to estimate the GPP of the Amazon-Cerrado Transitional Forest by the Vegetation Photosynthesis Model (VPM) using local meteorological data and remote sensing data from MODIS and Landsat 5 TM reflectance from 2005 to 2008. The GPP was estimated using Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) calculated by MODIS and Landsat 5 TM images. The GPP estimates were compared...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Amazon Basin; Cerrado; Carbon cycle; Climate change; Deforestation; Ecosystem function.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652015000401545

Cellulase activity and dissolved organic carbon release from lignocellulose macrophyte-derived in four trophic conditions
Provedor de dados: 58
Autores: Bottino,Flávia; Cunha-Santino,Marcela Bianchessi; Bianchini Jr.,Irineu.
Abstract Considering the importance of lignocellulose macrophyte-derived for the energy flux in aquatic ecosystems and the nutrient concentrations as a function of force which influences the decomposition process, this study aims to relate the enzymatic activity and lignocellulose hydrolysis in different trophic statuses. Water samples and two macrophyte species were collected from the littoral zone of a subtropical Brazilian Reservoir. A lignocellulosic matrix was obtained using aqueous extraction of dried plant material (≈40 °C). Incubations for decomposition of the lignocellulosic matrix were prepared using lignocelluloses, inoculums and filtered water simulating different trophic statuses with the same N:P ratio. The particulate organic carbon and...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Anaerobic decomposition; Cellulose; Carbon cycle; Aquatic macrophytes.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822016000200352